Minor tweaks to the GUI.

Implemented an ArrayList.
- Still need to implement a lot of methods...

Implemented a dynamic PriorityQueue. Should work with any kinds of objects. May be problematic with integers, due to the removing algorithm, I have to check that!
- Still need to implement a lot of methods...


Started to comment stuff!




Movement
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- Now all the settings are applied from the menu on the right
- All settings are used with the left mouse button
- Move the grid by holding right mouse button (if you have bigger grid than the display).
- Please select the start and goal node before pressing start (there's a glitch that activates the start button before you actually have placed them)
- When the simulation is done, you can recreate the grid


ToDo:
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- Add a memory support to remember the grid for later illustrations...
- The nodes in the path, should be clones not copies of the node. This way the world nodes can be left untouched, for tinting options on the path... (fading color for the oldest in the queue), or other nice features...